Carlsen prepares the advance of the b-pawn.
17. d4f4 Arjun decides to move the king to the side, giving the d4-square to the bishop if it becomes necessary to protect the e5-pawn. 17... f8e7  18. h4h5  18... h8f8 A solid move to protect the king. 19. e3d4 This move doesn't help White's position.